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/* SPDX-License-Identifier: BSD-3-Clause */
/*
* Copyright (c) 1988, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
* in_cksum.c,v 1.2 1994/08/02 07:48:16 davidg Exp
*/
#include "slirp.h"
/*
* Checksum routine for Internet Protocol family headers (Portable Version).
*
* This routine is very heavily used in the network
* code and should be modified for each CPU to be as fast as possible.
*
* XXX Since we will never span more than 1 mbuf, we can optimise this
*/
#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
#define REDUCE \
{ \
l_util.l = sum; \
sum = l_util.s[0] + l_util.s[1]; \
ADDCARRY(sum); \
}
int cksum(struct mbuf *m, int len)
{
register uint16_t *w;
register int sum = 0;
register int mlen = 0;
int byte_swapped = 0;
union {
uint8_t c[2];
uint16_t s;
} s_util;
union {
uint16_t s[2];
uint32_t l;
} l_util;
if (m->m_len == 0)
goto cont;
w = mtod(m, uint16_t *);
mlen = m->m_len;
if (len < mlen)
mlen = len;
len -= mlen;
/*
* Force to even boundary.
*/
if ((1 & (uintptr_t)w) && (mlen > 0)) {
REDUCE;
sum <<= 8;
s_util.c[0] = *(uint8_t *)w;
w = (uint16_t *)((int8_t *)w + 1);
mlen--;
byte_swapped = 1;
}
/*
* Unroll the loop to make overhead from
* branches &c small.
*/
while ((mlen -= 32) >= 0) {
sum += w[0];
sum += w[1];
sum += w[2];
sum += w[3];
sum += w[4];
sum += w[5];
sum += w[6];
sum += w[7];
sum += w[8];
sum += w[9];
sum += w[10];
sum += w[11];
sum += w[12];
sum += w[13];
sum += w[14];
sum += w[15];
w += 16;
}
mlen += 32;
while ((mlen -= 8) >= 0) {
sum += w[0];
sum += w[1];
sum += w[2];
sum += w[3];
w += 4;
}
mlen += 8;
if (mlen == 0 && byte_swapped == 0)
goto cont;
REDUCE;
while ((mlen -= 2) >= 0) {
sum += *w++;
}
if (byte_swapped) {
REDUCE;
sum <<= 8;
if (mlen == -1) {
s_util.c[1] = *(uint8_t *)w;
sum += s_util.s;
mlen = 0;
} else
mlen = -1;
} else if (mlen == -1)
s_util.c[0] = *(uint8_t *)w;
cont:
if (len) {
DEBUG_ERROR("cksum: out of data");
DEBUG_ERROR(" len = %d", len);
}
if (mlen == -1) {
/* The last mbuf has odd # of bytes. Follow the
standard (the odd byte may be shifted left by 8 bits
or not as determined by endian-ness of the machine) */
s_util.c[1] = 0;
sum += s_util.s;
}
REDUCE;
return (~sum & 0xffff);
}
int ip6_cksum(struct mbuf *m)
{
/* TODO: Optimize this by being able to pass the ip6_pseudohdr to cksum
* separately from the mbuf */
struct ip6 save_ip, *ip = mtod(m, struct ip6 *);
struct ip6_pseudohdr *ih = mtod(m, struct ip6_pseudohdr *);
int sum;
save_ip = *ip;
ih->ih_src = save_ip.ip_src;
ih->ih_dst = save_ip.ip_dst;
ih->ih_pl = htonl((uint32_t)ntohs(save_ip.ip_pl));
ih->ih_zero_hi = 0;
ih->ih_zero_lo = 0;
ih->ih_nh = save_ip.ip_nh;
sum = cksum(m, ((int)sizeof(struct ip6_pseudohdr)) + ntohl(ih->ih_pl));
*ip = save_ip;
return sum;
}
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